#!/bin/dash

max=$(cat /sys/class/backlight/intel_backlight/max_brightness)
cur=$(cat /sys/class/backlight/intel_backlight/brightness)
step=$((max*$1/100))
if [ $((cur+step)) -lt 0 ]; then
    setbrt 0
    exit 1
fi
if [ $((cur+step)) -gt "$max" ]; then
    setbrt "$max"
    exit 1
fi
setbrt $((cur+step))